This gene sequencing panel includes both sequencing and deletion/duplication (CNV) analysis for all coding regions of the included genes (unless otherwise noted). All analysis is performed utilizing next-generation sequencing (NGS) technology. All variants are classified according to American College of Genetics and Genomics (ACMG) guidelines.

Duchenne and Becker muscular dystrophies are two related conditions that primary affect skeletal muscles which are used for movement and heart muscle. Duchenne and Becker occur almost exclusively in males. Duchenne and Becker muscular dystrophies have similar signs and symptoms and are caused by different mutations in the same gene. Duchenne and Becker muscular dystrophies together affect 1 in 3500 to 5000 newborn males worldwide and are caused by mutations in the DMD gene. Approximately 60% of pathogenic variants in the DMD gene are deletions of one or more exons, approximately 5% are duplications of one or more exons, and approximately 35% are small pathogenic variants within the exon.

DMD

The Agilent Sureselect DMD targeted sequence capture method was used to enrich the entire DMD gene, which includes all exons and introns from this sample’s genomic DNA. DNA was analyzed by next-generation sequencing (NGS) on the Illumina MiSeq or NovaSeq™ 6000 with 2x150 paired-end reads. Primary data analysis is performed using Illumina bcl2fastq converter v2.19. Secondary analysis is performed using Illumina DRAGEN Bio-IT Platform v3.10.8. Tertiary analysis for SNVs is performed using SnpEff v5.0 and Revvity Omics' internal ODIN v1.01.66 software. Deletions and duplications within the DMD gene were assessed using BioDiscovery’s NxClinical v6.1 software (El Segundo, CA). The interpretation of variants is based on our current understanding of the DMD gene. Interpretations may change over time as more information about this gene becomes available. Variants are evaluated by their frequency in databases such as the Genome Aggregation Database (gnomAD), Human Gene Mutation Database (HGMD), and ClinVar. Variants that have a frequency greater than expected given the prevalence of disease are considered to be benign. Benign and likely benign variants are not reported. Intronic variants beyond +/-3 are not reported unless known or suspected to be pathogenic. Some complex variants may not be detected, including complex rearrangements such as inversions or insertions. In some cases, due to the complexity of the sequence, not all variants in the flanking intronic regions are able to be analyzed. This assay is not designed to detect mosaicism; possible cases of mosaicism may be investigated at the discretion of the laboratory director. Possible diagnostic errors can include sample mix-ups, genetic variants that interfere with analysis, and other sources. A list of all variants identified in this individual is available upon request.